On September 10, 2017, while exploring Sibelius Seamount, the team observed this garden of coral at a depth of 2,465 meters (8,080 feet). This garden was one of two high-density communities observed during the dive. Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download larger version (jpg, 1.8 MB).
This hatchetfish was spotted in the water column at a depth of 500 meters (1,640 feet) during midwater transects on September 10, 2017. Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download larger version (jpg, 335 KB).
This vibrant yellow glass sponge (Bolosoma sp.) was observed at a depth of 2,479 meters (8,133 feet) while exploring Sibelius Seamount. Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download larger version (jpg, 1.0 MB).
Today’s dive was the best of both worlds: exploration of both the seafloor and the water column. For the benthic portion of the dive, remotely operated vehicle (ROV) Deep Discoverer (D2) reached the seafloor of Sibelius Seamount at a depth 2,600 meters (8,530 feet), slowly climbed up the steep slope of a circular outcrop, and finally moved up the ridge to the flat summit of the seamount. Early on in the dive, the team observed a talus (broken rocks) slope with a relatively low density of animals, including jellyfish, a tumbling snail, sea cucumbers, and crinoids. As D2 moved up the slope, the density of animals greatly increased and we observed an ensemble of benthic organisms, including a variety of corals, sponges, echinoderms, sea stars, fishes like sorceress and cusk eels, and more. In total, the team observed two separate high-density communities.
After the benthic portion of the dive, the ROV pilots maneuvered D2 up through the water column and conducted 100-meter midwater transects at depths 800, 700, 600, 500, 400, and 300 meters. During the ascents between transect depths, the ROV tether was kept behind the vehicle so as not to disturb the water, and the ROVs ascended slowly at a speed of about 10 meters per minute. While exploring at various depths in the water column, the team observed siphonophores, ctenophores, salps, jellies, an eel, a hatchetfish and other fishes, and pteropods. D2 also got inked by a squid! This was the first of seven dives during this expedition that will be wholly or partially dedicated to water column exploration. The team is excited to continue exploring this largely unknown biome.